Here in east cental Iowa I have seen "introduced" river otter demolish trout streams and ponds. I have seen them go right by smaller fish and deliberately harass larger fish just to prove they can kill them. They will usually play them to death, grab em, bring em' on the bank, take a bite out of em' and go back in the water and do it all over again. They are lethal until they get bored, then they will move on. If you got em', you are in trouble until they move on or you kill them.
